Flow splitters are well-known in such applications as hydrology, pulverulent material, and oil-and-gas handling and processing. In hydrology applications, the most common flow splitter device is a weir baffle. Weirs are used to divert water flow for further dilution and treatment and to separate a two-phase stream consisting of a liquid phase and a solid phase. Weirs are effective in these applications because the split of the liquid and solid phases is unlikely to become unbalanced.
Unbalanced flow is also not a concern in pulverulent material applications. In these applications, a flow splitter typically works by swirling a transport medium like air within the confines of a conical-shaped body such that the material entrained in the medium is distributed to various outlets disposed around the face of the conical-shaped body. Another flow splitter makes use of a v-shaped plug for distributing an inlet stream of pulverulent material to various outlets extending at an angle of less than 90 degrees to the inlet flow. This type of splitter is typical of flow splitters in general, requiring greater length relative to the diameter of the inlet stream, thereby increasing the footprint of the splitter.
In oil-and-gas applications, balancing the split of both phases of an input stream is important for safe, continuous operation. However, accurately dividing a two phase stream into an equal number of separate trains or pipelines is difficult and costly, requiring a downstream degassing vessel and elaborate instrumentation for subsequent splitting. Additionally, it is extremely difficult—if not impossible—to balance the split of both phases of the inlet stream. This imbalance presents an increased risk of failure, especially during slugging operations.
One standard splitting approach used in oil-and-gas applications involves piping the inlet stream into two symmetrical pipelines, each of which connects to a downstream degassing vessel. Although the two flow paths are symmetrical, the gas phase of the split can become unbalanced due to vortex flow in the piping just ahead of the split, the rheological properties of the stream, and the geometric complexities of the equipment involved. This unbalanced gas flow can overload one of the degassing vessels.
A second standard approach pipes the inlet stream into a degassing vessel that contains outlets leading to symmetrical pipelines and processing vessels. This approach, however, requires controlling inlet stream momentum, stream retention time, and outlet flow. The gas phase of this split also can become unbalanced for the same reasons as the first approach above. Variations of this second approach—all of which fail to equalize the loads before splitting—include placing a weir baffle inside a degassing vessel to split the inlet stream into two compartments which, in turn, are split into two pipes. The two phases are then recombined at the outlet side with the liquid phase flow rate controlled through an adjustable valve.
A third standard approach employs a centrifugal separator inlet device that consists of pairs of cylindrical tubes connected by a manifold to a vessel inlet nozzle. A stream enters the tubes tangentially, creating centrifugal force that causes stream separation by spinning the liquid phase of the stream outward against the walls of the tubes. While this approach controls inlet stream momentum by redirecting the stream and dissipating its energy, it is costly and requires a relatively large footprint to implement.
A need exists, therefore, for a flow splitter that eliminates the use of expensive control instrumentation, controls inlet momentum and impact forces, eliminates unbalanced load in outlet streams, and reduces cost, footprint area, and weight relative to standard degasser installations. None of the prior art alone or in combination meets this need or renders the present invention obvious.
For additional information relating to flow splitters, reference may be had to the following previously issued United States patents.
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